Ingenium Technologies

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Engineering Services

Crystal Autoclave Pressure Seal

Ingenium was hired by an industrial manufacturer to solve an expensive seal problem on their crystal autoclave equipment. The enormous equipment involved and the stringent crystal growth operating characteristics are intriguing:

Crystal Autoclave Equipment

Autoclave Vessel:

  • vessel weighs 75 ton
  • vessel lid weighs 5 ton
  • clamps that secure the lid to the vessel weigh 5 ton
  • 50’ tall
  • 3.5’ diameter

Vessel Operating Parameters:

  • 570~750° F
  • 29,000 P.S.I.
  • 6~10 weeks of convection

Pressure Seal

The client hired Ingenium to solve the problem of the autoclave vessel seal failure. The metal ring seal is placed between the lid and the vessel and clamped securely to ensure the vessel does not leak for the duration of the crystal growing process.   The current seal was lasting only one cycle and was expensive to replace each time. The seal under such extreme pressure and temperature conditions would not last indefinitely; however, the customer desired to extend the life of the seal for multiple batches before requiring a replacement.   

By completing thorough analysis Ingenium determined the exact failure mode. Surprisingly the extreme pressure was not the true cause of the failure as initially thought. The more crucial cause of failure was determined to be the unequal thermal growth of the vessel and lid resulting in the upper “ear” of the seal becoming stressed beyond the material property limits. 


Redesign Shows the Larger Relief Radius

Once the cause for failure was understood Ingenium provided a redesign solution. Utilizing materials engineering and further analysis, a larger relief radius was incorporated to the “ears” of the ring and for a portion of the ring itself. This profile provided clearance between the lid and vessel that allowed deflection over a larger zone of the ring seal thus reducing stress concentration from the corner where the “ears” meet the seal body.

Ingenium provided drawings of the new seal and outsourced the build of the new ring seal prototypes. The final design was a success and the customer was able to achieve the desired seal that could withstand multiple uses in this harsh environment.